1. Field of the Invention
The invention relates to needle thread snubbing devices for use on sewing machines.
2. Description of the Prior Art
It is well known to dispose a needle thread snubbing device between a sewing machine needle and a needle thread take-up for controlling the size of a needle thread loop presented to the loop taker of a lockstitch sewing machine. However, many of the prior needle thread snubbing devices have had a drawback in that they snubbed needle thread not only during loop presentation but also during stitch setting thereby requiring thread tensioning devices to be set at correspondingly higher values which increased the possibility of thread breakage. One exception is the automatically operable inertial thread snubbing device of U.S. Pat. No. 3,496,895 of S. J. Ketterer issued Feb. 24, 1970 and assigned to The Singer Company. Such inertial snubbing device, however, while effective to apply a snubbing action during loop presentation and remove or greatly reduce the snubbing action during stitch setting provided for point contact only at the snubber with the needle thread and sometimes resulted in the thread being pinched in the device. The device of the patent was also difficult to thread. Various other previously proposed needle thread snubbing devices are driven through linkage arrangements by the operating mechanism of a machine to effect snubbing when necessary. However, such thread snubbing devices and associated mechanism are complex and costly to manufacture.